1. Field of the Invention
This invention relates to heat exchangers for use in an air conditioning system for a vehicles, and more particularly, to reinforcing means for reinforcing tanks against increasing pressure within such heat exchangers.
2. Description of the Prior Art
FIG. 1 shows a conventional heat exchanger used in an air conditioning system, such as an evaporator or a condenser. In FIG. 1, heat exchanger 10 has upper tank 101, lower tank 102, and heat exchanger core 103 disposed between upper tank 101 and lower tank 102. Heat exchanger core 103 has a plurality of heat transfer tubes 104 spaced from one another and disposed in parallel to one another. Upper tank 101 has upper wall 101a and lower wall 101b, which are united to each other. Upper tank 101 is divided into three chambers, such as first upper chamber 180, second upper chamber 190, and third upper chamber 200, by partition plates 31 and 32. Lower tank 102 is divided into two chambers, such as first lower chamber 210 and second lower chamber 220, by partition plate 33. Lower wall 101b of upper tank 101 and upper wall 102a of lower tank 102 are provided with a plurality of connection holes 101c and a plurality of connection holes 102c, respectively, for interconnecting a plurality of heat transfer tubes 104 therebetween. Inlet pipe 105 and outlet pipe 106 are connected to upper tank 101. For example, a heat exchanger medium may be introduced via inlet pipe 105 into first upper chamber 180 and may flow down through heat transfer tubes 104 until it reaches first lower chamber 210 of lower tank 102. The medium then may flow back into second upper chamber 190 through heat transfer tubes 104.
Partition plate 31 includes a plurality of notched portions 31a formed with a predetermined pitch, width, and depth. Partition plate 32 includes a notched portion (not shown) formed in the center thereof. Further, upper tank 101 and lower tank 102, respectively, include a plurality of reinforcement plates 41 therein. Reinforcement plates 41 include notched portions 41a formed in the center thereof and a plurality of holes 41b therein. A plurality of holes 41b are formed with a predetermined number, pitch, and diameter, so that a heat exchanger medium may pass freely through holes 41b of reinforcement plates 41.
In a method for assembling upper tank 101 and lower tank 102, partition plate 32 is connected with partition plate 31 at right angles to each other, so that the notched portion (not shown) of partition plate 32 fixedly inserts into center notched portion 31a of partition plate 31. Thereafter, a plurality of reinforcement plates 41 may be connected with partition plate 31 at right angles, so that notched portions 41a of reinforcement plates 41 fixedly insert into notched portions 31a of partition plate 31 shown in FIGS. 3, 4 and 5, to prevent the movement thereof during brazing. Finally, assembled heat exchanger 10 may be placed in a brazing furnace, such that all of its parts may be simultaneously brazed together.
Further, referring again to FIG. 2, the heat exchanger medium flows from second upper chamber 190 of upper tank 101 through heat transfer tubes 104 and into second lower chamber 220 of lower tank 102 and then flows back to third upper chamber 200 through heat transfer tubes 104. When the heat exchanger medium flows through heat transfer tubes 104, heat is exchanged between the heat exchanger medium and air flow 17 passing across heat transfer tubes 104, as shown in FIG. 2.
Generally, in the arrangement described above, upper tank 101 and lower tank 102 easily expand outward due to increasing pressure within the heat exchanger because upper tank 101 and lower tank 102 are formed with flat surfaces. It may be possible to overcome this disadvantage by forming the upper wall and lower wall of the tanks with an uneven surface or forming the upper wall and lower wall with thick plate members to increase the pressure strength of tanks. However, this construction method requires making a complex and expensive working die, or increasing the net weight of the heat exchanger.
In view of these disadvantages, the tanks may be provided with at least one reinforcement plate, such as reinforcement plate 41, and reinforcement plate 41 may be secured to the inner surface of the tanks by brazing to increase the internal pressure resistance of the tanks. Nevertheless, reinforcement plate 41 must be secured to partition plate 31 before brazing heat exchanger 10 in a brazing furnace to prevent movement of reinforcement plate 41. This process, however, is also complex and time consuming.